We discovered one or more bugs in your app when reviewed on iPad running iOS 10.3.1 on Wi-Fi connected to an IPv6 network.
Specifically, your app failed to load and displayed a blank screen indefinitely.
To resolve this issue, please run your app on a device while connected to an IPv6 network (all apps must support IPv6) to identify any issues, then revise and resubmit your app for review.
If we misunderstood the intended behavior of your app, please reply to this message in Resolution Center to provide information on how these features were intended to work.
For apps, uninstall all previous versions of your app from a device, then install and follow the steps to reproduce the issue. For , install the new version as an update to the previous version, then follow the steps to reproduce the issue.
For information about supporting IPv6 Networks, please review Supporting IPv6 DNS64/NAT64 Networks and About Networking.
App Store Review
You haven't provided any information beyond the text from the rejection notice.
It can be very difficult to troubleshoot app store rejections, so you'll need to provide more information in order to get help with this issue.
For example, have you been able to reproduce the issue that Apple identified?
That is, "Specifically, your app failed to load and displayed a blank screen indefinitely."
Also, it's not clear if this is a general issue or only an issue with the specific scenario listed by Apple (iPad running iOS 10.3.1 on Wi-Fi connected to an IPv6 network). The rejection note seems to suggest that this is specifically related to IPv6.
Do you think that's the case?
The iPad simulator is not a good test environment for these sorts of things. You need to run on a real device. That is the only way you are going to really figure out what is going wrong. See this page for info on debugging options > https://software.intel.com/en-us/xdk/docs/intel-xdk-debug-and-test-overview <
Your iPad doesn't need to be running 10.3.1 to test for IPv6 compliance.
There is already some information in the rejection notice about supporting IPv6, but in case it helps, here is an Apple support page that provides information about the requirement to support IPv6 networks as well as how to test for compliance with this requirement. Here is a stickied post on Apple's developer forums that has more information about this issue. I also noticed a few thread like this one, where invalid rejections were resolved by contacting Apple. If you are still having a problem, I suggest that you follow the instructions to check for IPv6 compatibility first, then if you don't find any compatibility problems in your testing, contact Apple.